Equibles

BIIB

Biogen Inc.

Company with tickers: BIIB

CIK
875045
CUSIP
09062X103
Shares Outstanding
147,637,117
13F Activity (30d)
685 filings 673 filers
Holders: 996
Total Value: $25,164,384,010
Total Shares: 137,262,776
Showing 1–100 of 1,037 holdings by value · page 1 of 11

Institutional Ownership Trend

25 quarters

Holder Concentration

Across 996 13F filers · Δ vs Dec 31, 2025
Top Holder
11.6%
Jun 2023 → Mar 2026 · range 10.9% – 12.8%
−0.4 pts
Top 5
43.9%
Jun 2023 → Mar 2026 · range 42.8% – 46.7%
+0.1 pts
Top 10
57.0%
Jun 2023 → Mar 2026 · range 53.5% – 61.3%
+1.8 pts
HHI
478
Jun 2023 → Mar 2026 · range 445 – 546
Broadly held +8

Quarterly Activity

vs Dec 31, 2025
New
138
Increased
392
Decreased
290
Sold Out
137
Unchanged
176
Holder count: +1
Institutional value: -1.5%
Shares held: -5.4%

Top Buyers

vs Dec 31, 2025
Institution Added Now Holds Open
Mega FMR LLC +3,381,678 12,807,541
Mega BlackRock, Inc. +1,163,231 15,974,601
Mega AQR CAPITAL MANAGEMENT LLC +394,941 1,923,557
Mid Artemis Investment Management LLP +344,726 571,571
Large LMR Partners LLP +261,801 270,431

Top Sellers

vs Dec 31, 2025
Institution Sold Now Holds Open
Large Point72 Asset Management, L.P. −3,000,375 814,317
Mega MILLENNIUM MANAGEMENT LLC −991,622 281,764
Mega SUSQUEHANNA INTERNATIONAL GROUP, LLP −882,785 1,434,199
Mega BARCLAYS PLC −761,133 731,474
Mega WELLINGTON MANAGEMENT GROUP LLP −589,628 2,961,641

Top New Positions

vs Dec 31, 2025
Institution Acquired Value (USD) Open
Mega VANGUARD CAPITAL MANAGEMENT LLC 9,537,417 $1,748,494,658
Mega VANGUARD PORTFOLIO MANAGEMENT LLC 6,531,727 $1,197,461,510
Mega VANGUARD FIDUCIARY TRUST CO 825,531 $151,344,598
Mega Vanguard Global Advisers, LLC 343,768 $63,022,987
Large Swedbank AB 289,840 $53,136,366

Top Sold-Out Positions

vs Dec 31, 2025
Institution Previously Held Last Value (USD) Open
Mega VANGUARD GROUP INC 17,447,092 $3,070,513,719
Mega NORGES BANK 2,638,834 $464,408,395
Mid Pacer Advisors, Inc. 1,145,890 $201,665,181
Large HRT FINANCIAL LP 384,265 $67,626,797
Large Jain Global LLC 353,173 $62,154,916
Filter: New 138 Increased 392 Reduced 290 Sold out 137 Unchanged 176
Showing 100 of 1,037
All Common Calls Puts
Export CSV
Holder Value (USD) % of 13F Shares Open
Mega BlackRock, Inc. $2,928,623,591 11.64% 15,974,601
Mega PRIMECAP MANAGEMENT CO/CA/ $2,705,512,091 10.75% 14,757,607
Mega FMR LLC $2,348,006,489 9.33% 12,807,541
Mega VANGUARD CAPITAL MANAGEMENT LLC $1,748,494,658 6.95% 9,537,417
Mega STATE STREET CORP $1,314,095,140 5.22% 7,167,922
Mega VANGUARD PORTFOLIO MANAGEMENT LLC $1,197,461,510 4.76% 6,531,727
Mega GEODE CAPITAL MANAGEMENT, LLC $796,129,223 3.16% 4,342,602
Mega WELLINGTON MANAGEMENT GROUP LLP $542,957,642 2.16% 2,961,641
Mega MORGAN STANLEY $397,998,422 1.58% 2,170,940
Mega JPMORGAN CHASE & CO $369,594,922 1.47% 2,016,009
Mega AQR CAPITAL MANAGEMENT LLC $352,645,701 1.40% 1,923,557
Mega Invesco Ltd. $319,957,589 1.27% 1,745,255
Large Boston Partners $311,675,298 1.24% 1,700,078
Mega NORTHERN TRUST CORP Bank $265,201,323 1.05% 1,446,579
Mega UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC $252,549,536 1.00% 1,377,568
Mega Legal & General Group Plc $247,464,699 0.98% 1,349,832
Mega T. Rowe Price Investment Management, Inc. $212,844,113 0.85% 1,160,989
Mega BANK OF AMERICA CORP /DE/ Bank $211,997,125 0.84% 1,156,369
Mega CHARLES SCHWAB INVESTMENT MANAGEMENT INC $210,718,402 0.84% 1,149,394
Mega VAN ECK ASSOCIATES CORP $197,970,916 0.79% 1,079,861
Mega DIMENSIONAL FUND ADVISORS LP $197,834,883 0.79% 1,079,119
Mega DEUTSCHE BANK AG\ Bank $195,031,581 0.78% 1,063,828
Mega GOLDMAN SACHS GROUP INC $192,697,062 0.77% 1,051,094
Large Pictet Asset Management Holding SA $167,440,422 0.67% 913,328
Mega VANGUARD FIDUCIARY TRUST CO Bank $151,344,598 0.60% 825,531
Large Point72 Asset Management, L.P. $148,427,084 0.59% 809,617
Large Alyeska Investment Group, L.P. $147,589,816 0.59% 805,050
Mega SUSQUEHANNA INTERNATIONAL GROUP, LLP $146,425,671 0.58% 798,700
Mega Amundi $144,982,312 0.58% 790,827
Mega Bank of New York Mellon Corp Bank $144,559,917 0.57% 788,523
Large Robeco Institutional Asset Management B.V. $139,912,689 0.56% 763,174
Large FRED ALGER MANAGEMENT, LLC $134,416,456 0.53% 733,194
Mega MASSACHUSETTS FINANCIAL SERVICES CO /MA/ $132,112,911 0.52% 720,629
Large Employees Provident Fund Board $129,100,252 0.51% 704,196
Mega FIRST TRUST ADVISORS LP $123,556,720 0.49% 673,958
Mega PRICE T ROWE ASSOCIATES INC /MD/ $123,276,041 0.49% 672,427
Large Balyasny Asset Management L.P. $119,172,933 0.47% 650,046
Large AustralianSuper Pty Ltd $112,966,662 0.45% 616,193
Mid Artemis Investment Management LLP $104,786,111 0.42% 571,571
Mega BARCLAYS PLC $101,101,727 0.40% 551,474
Mega ROYAL BANK OF CANADA Bank $97,417,340 0.39% 531,377
Mega UBS Group AG $95,964,085 0.38% 523,450
Large Zurcher Kantonalbank (Zurich Cantonalbank) Bank $95,726,676 0.38% 522,155
Large Caisse de depot et placement du Quebec $95,092,171 0.38% 518,694
Mega CITIGROUP INC $91,757,947 0.36% 500,507
Mega SUSQUEHANNA INTERNATIONAL GROUP, LLP $90,785,016 0.36% 495,200
Mega BNP PARIBAS ARBITRAGE, SA $86,360,896 0.34% 471,068
Mega HSBC HOLDINGS PLC $85,001,319 0.34% 463,652
Mega Swiss National Bank Bank $78,941,898 0.31% 430,600
Mega National Pension Service Pension $73,637,611 0.29% 401,667
Large Candriam S.C.A. $69,989,527 0.28% 381,768
Mid Patient Capital Management, LLC $69,617,917 0.28% 379,741
Mega Nuveen, LLC $65,785,769 0.26% 358,838
Mega Sumitomo Mitsui Trust Group, Inc. $65,318,829 0.26% 356,291
Mega Vanguard Global Advisers, LLC $63,022,987 0.25% 343,768
Mega California Public Employees Retirement System Pension $62,497,746 0.25% 340,903
Mega Mitsubishi UFJ Asset Management Co., Ltd. $61,307,935 0.24% 334,413
Large LSV ASSET MANAGEMENT $61,184,370 0.24% 333,739
Large ADAGE CAPITAL PARTNERS GP, L.L.C. $61,132,671 0.24% 333,457
Mega VICTORY CAPITAL MANAGEMENT INC $58,809,514 0.23% 320,785
Large Man Group plc $58,435,520 0.23% 318,745
Mega FIL Ltd $58,309,206 0.23% 318,056
Mega Fisher Asset Management, LLC $57,312,257 0.23% 312,618
Mega CITADEL ADVISORS LLC $54,980,667 0.22% 299,900
Large Gotham Asset Management, LLC $54,712,455 0.22% 298,437
Large Swedbank AB Bank $53,136,366 0.21% 289,840
Mid CAUSEWAY CAPITAL MANAGEMENT LLC $51,475,947 0.20% 280,783
Mega RHUMBLINE ADVISERS $50,496,048 0.20% 275,438
Mid KAMES CAPITAL plc $47,433,887 0.19% 258,735
Mega VANGUARD ASSET MANAGEMENT, Ltd $45,791,800 0.18% 249,778
Large ACADIAN ASSET MANAGEMENT LLC $45,555,488 0.18% 248,489
Mid THOMPSON SIEGEL & WALMSLEY LLC $45,528,722 0.18% 248,343
Large KBC Group NV $43,026,083 0.17% 234,692
Large MARSHALL WACE, LLP $42,143,716 0.17% 229,879
Mid Sofinnova Investments, Inc. $42,078,084 0.17% 229,521
Large CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM Pension $40,458,547 0.16% 220,687
Large BNP PARIBAS ASSET MANAGEMENT Holding S.A. $39,495,881 0.16% 215,436
Large Qube Research & Technologies Ltd $39,034,806 0.16% 212,921
Mega ALLIANCEBERNSTEIN L.P. $39,030,407 0.16% 212,897
Large RENAISSANCE TECHNOLOGIES LLC $37,288,588 0.15% 203,396
Large Hudson Bay Capital Management LP $36,916,612 0.15% 201,367
Mid Logos Global Management LP $36,666,000 0.15% 200,000
Large KLP KAPITALFORVALTNING AS $36,515,119 0.15% 199,177
Large SG Americas Securities, LLC Broker-Dealer $35,871,814 0.14% 195,668
Mega PRINCIPAL FINANCIAL GROUP INC $34,293,526 0.14% 187,059
Mega BARCLAYS PLC $32,999,400 0.13% 180,000
Large Allianz Asset Management GmbH $32,641,723 0.13% 178,049
Mega JANE STREET GROUP, LLC $31,477,761 0.13% 171,700
Large PRUDENTIAL FINANCIAL INC $30,045,402 0.12% 163,887
Large LMR Partners LLP $28,287,819 0.11% 154,300
Large IEQ CAPITAL, LLC $27,880,093 0.11% 152,076
Large ExodusPoint Capital Management, LP $27,864,876 0.11% 151,993
Large Aberdeen Group plc $27,709,228 0.11% 151,144
Mid LETKO, BROSSEAU & ASSOCIATES INC $27,658,080 0.11% 150,865
Mega FRANKLIN RESOURCES INC $26,481,647 0.11% 144,448
Large PANAGORA ASSET MANAGEMENT INC $26,044,776 0.10% 142,065
Large O'SHAUGHNESSY ASSET MANAGEMENT, LLC $25,908,928 0.10% 141,324
Small Palo Alto Investors LP $25,798,014 0.10% 140,719
Mega SUSQUEHANNA INTERNATIONAL GROUP, LLP $25,721,015 0.10% 140,299
Mega CITADEL ADVISORS LLC $25,316,588 0.10% 138,093
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